Percussion-plunger.



l. A. DORAN.

PERCUSSION PLUNGER. v APPLICATION mm 11m15.191s.

1 ,287,9 1 6 Patepted Dec. 17, 1918.

2 Y l r/ y tion.

Enron.

JAMES A. DURAN, 0F PROVIDENCE, RHODE ISLAND.

PIERCUSSION-PLUNGER.

Specication of Letters Patent.

Patented Dec. 17, 1918.

Application led April 6, 1918. Serial No. 227,021.

To all whom t may concern:

Be it known that I, JAMES A. DonAN, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented a certain new and useful Improvement in Percussion-Plungers, of which the following 1s a full, clear, and exact description.

This invention relates to percussion plungers for all types of projectiles, whether used in the nose, as is common in the fuse of a shrapnel shell, or in the base, as in high explosive shells. v

The main object of the invention is t provide a plunger which will render the shell proof against accidental explosion, and also insure explosion on impact after it is tired from the gun and reaches its destina- Various plungers which have been designed for this purpose are not wholly p reliable. Some fail to give the safe protection that is so highly important, and others fail to cause an explosion on impact.

Another object is to produce a percussion plunger almost entirely by the simplest of machine operations, namely, turning and drilling, thus reducing the cost of manufacture, and permitting production in large quantities in relatively short time without necessitating the installation of special machinery.

The invention consists in a percussion plunger provided with a central bore to which is loosely fitted a tapered ring pin adapted to be forced into the bore to`thereby assume a fixed armed position by frictional engagement when the shell containing the plunger is projected or red from the gun or other projecting means, as I will proceed now to explain and finally claim.

,In the accompanying drawings illustrating the invention, in the several fi res of which like parts are similarly designated, Figure l is a longitudinal section of a fuse block such as is used in detonators of higheXplosive shells provided with the plunger of the invention and showing the plunger in unarmed position. Fig. 2 is a view similar to Fig. l but showing the plunger in armed position and advanced into position for firing the fulminate cap or primer. Fig.

3 is a perspective view of the plunger and its parts disassembled. Fig. 4 is a fragmentary sectional elevation showing the method of retaining the shearable pin in place. Fig. 5 is a fragmentary sectional elevation showing the plunger applied to a combination timing and percussion fuse. Figs. 6 and 7 are, respectively, a longitudinal section and a sectional elevation illustrating modiications in which the plunger and a restraining spring are assembled as a unit for ready application to a fuse block.

The invention may in practice assume various specific embodiments to suit special conditions and types of shells, but for purposes of illustration of the principle of the invention, I have shown a plunger 1 having a central tapered bore 2. Fitted loosely to this bore is a complementally tapered liring pin 3. The firing pin is retained in normal, unarmed position by means of a transverse shearable locking pin 4 passing through a hole in it and through a hole in the plunger l and having the edges around the hole turned or peened in as at 5, so that the pin will always remain iixed in the plunger, as shown most clearly in Fig. 4. This firing pin has the ring point 6, and the pin holds the firing pin in such relation to the plunger that its firing point 6 is flush with or slightly back of the forward end of the plunger. The pin 4 is of such diameter that the projective force or set of the gun will cause the plunger 1 to shear 1t and drive the ring pin 3 into the plunger, as shown in Fig. 2, the tapers making a very firm hold between firing pin and plunger, but it is not of a diameter so small that accident, such as dropping of the shell during loading or transportation, will shear it.

The plunger l is provided with one or more vents 7 to permit air to pass from one end to the other as it slides in the chamber o f the fuse block, thus precluding the possibility of the formation of an air-cushion or a vacuum at either end of the plunger to interfere with its proper operation. If desired, however, the vents may be omitted as in Fig. 2, in which case the plunger would nbe made to so fit the chamber as to allow air to escape between it and the wall of the chamber of the fuse block.

In `order to guard against premature explosion of the shell which might be caused by advancing of the plungerin armed position due to decreased momentum of the shell in transit, a spiral or other suitable spring 8 is interposed between a shoulder 9 on v,the plunger andthe end of the chamber in the fuse block, but this Yspring is not suiiciently stiff to unduly retard the advancement of the plunger 'as desired upon impact.

For Yconvenience in installing these plungers in the chambers of fuse blocks, 1 may make the plunger 1 and spring 8 as a unit, by assembling the two within a lsleeve or casing 10 adapted to t the chamber of the fuse block. Two forms which this sleeve or casing 10 may take, among others, are shown in Figs. 6 and 7, in the former the sleeve or casing being closed at the rear end as at 11, and in the latter being opened as at 12 and having an inturned annular lip 13 closely fitting a shouldered recess 14 at the end of the plunger l.

In operation, the plunger is assembled in the chamber of the fuse block as described,

the spring 8 holding it with the rearwardly projecting end of the firing pin 3 in contact with therear wall 15 of the chamber of the fuse block, as shown in Fig.. 1. lli/'henV the shell containing the fuse block and plunger is fired, the set .of the gun, 'or projective Vforce exerted upon the shell, forces the plunger rearwardly and shears the pin .4 and drives the corresponding tapers of the borefof the plunger and of the firing pin together with such force as to make their separation practically impossible for all intended purposes. rllhe .spring 8 then holds the plunger in its rearmost position during transit Iof the shell, but whenY the shell strikes its objective the impact advancesV the plunger so that the point 6 of the firing pin 3 explodes the cap 16 and hence'the explosive charge of the'shell. Y There is no danger of the force of impact releasing the grip of Y the tapers of the bore and pin for the reason that the force exerted by the Vset of the. gun is far in excess of the blow required to explode the its objective.

As shown in Fig. 5, the plunger is adapted for use in a combination timer and percus-v sion fuse such as isused on shrapnel shells, and operates 1n a chamber 17 therein the Vsame mannerjas alcoveV described with respect to its operationiin the fuse block.

As y'shown in Fig.. 6, the bore 2 may be tapered for about three-quarters' of its length only, as at V18,1;he remainder thereof being cylindrical as at 19,' and the ri-ng pin .'3 provided with a eomplementally tapered portion 20 and-cylindrical portionZl, theV cylindrical portionsV 20 andQl fitting with'V anv easy sliding fit sok as to ive aV directive bearing to the gng pin. -After ill:.ei-7911.1V iS sheared, the'peened over V,portion 5 at each end thereof prevents the 'severed pin `ends ifrom workingoutwardly. 'Y

' .'65 led iS V@ftheruilt. type. shown in, .,wigsl'eY be obi/Cors .that when? the plunger primer when the shell strikes,

and 7, the sleeve or casing 10 entirely fills the chamber of the'b'lock or fuse, Iand the plunger slides withinV theV sleeve or casing.

'The plunger of the present invention has Iadvantages .over others in that it functions positively, because it depends on two absolutely reliable mechanical operations, viz., shearing of a pin, and locking of tapers. Its arming is not governed by springs, which cause Vuncertainties in other plungers. It is free from a n'iultiplicity of moving parts, which is commonV in other plungers, and which ygives several chances of failure. By reducing the number of'parts, I also greatly reduce expense yof manufacture and also increase production.

The simplicity ofthe plunger permits of accurate mechanical inspection, thus obviating the necessity for expensive time-consuming tests. Y n

Thel transverse pin precludes accidental explosion of the shell, as only its intentional projection can shear this pin and place the firing pin in armed position. I'prefer to use copper as the material from which to make this pin because of its durable, nonvcorrosive quality. Y As already sta-ted, the plunger of the invention may assume various forms to adapt it for the special type of shell and fuse block or fuse with which it is used, and `I lo not Y ,without departing' from the.Y spirit of the invention or the scope of the claims fol- Y lowing.

WhatI claim is Y Y Y 1. -AY percussion plunger, having a .tapered bore-and previded with a tapered firing pin adapted to be retained in armed position by frictional engagement therewith.

2. A. percussion plunger, provided with a f tapered central bore, land a tapered .firing pin fitted in said bore and adapted to have a limited longitudinal movement therein whereby frictional engagementis obtained to hold said. pin in armed position. v

3. A percussion plunger, adaptedto have allongitudinal sliding movement within the chamber of an ammunition fuse, said plunger provided with aj taperedcentral bore, a

taperediring pin vfitted-.loosely in said bore and held in unarmed position therein by' a transversev pin and adapted upon the shearin of said pin by projectiveforce to assume a xed armed `positionbyY frictional: engage- Y Infant with-said here.

' 4. A percussionplunger, providedA with aV ktapered central bore, a tapered firing Vpini held bya Atransverse'shearable pin in unarmed po- Sition insaid"plunger,jsaid transverseY pin adapted to 1 be mhcari-zd;byv projectivei force to said'ng pineto.' assume a fixed armed ing provided with registering transverse,

holes and a pin passing through said holes, the outer extremities of the hole in said plunger being turned or peened over upon the pin ends.

7 A percussion plunger, provided with a central longitudinal bore, a firing pin fitted to said bore, said plunger and ring pin being provided with registering transverse holes, and a pin passing through said registering transverse holes and adapted to be sheared by the coaction of the plunger and firing pin in the act of firing and its severed parts held from withdrawal by peening or turning over the metal of the plunger upon its ends.

8. A percussion plunger, a restraining spring therefor, and a casing fitted to said plunger and' adapted to engage said spring to hold the same in operative relation to said plunger to thereby forni an operative unit.

In testimony whereof I have hereunto set my hand this 1st day of April A. D. 1918.

JAMES A. DORAN.

Witnesses:

K. M. Dolmar, E. S. DONOVAN.

Copies of this patent may be obtained for ve cents each, by addressing the commissioner of Patents,

Washington, D. G. 

